Tuning apparatus



July 20, 1937. v. H. SEVERY TUNING APPARATUS Filed Jan. 11, 1956 8SheetsSheet 1 V/cfor HT Java/"y July 20, 1937. I 1 v. H. SEVERY2,087,485

TUNING APPARATUS Filed Jan. 11, 1936 8 Sheets-Sheet 2 wuc ntoo a:

July 20, 1937.

V.H. SEVERY TUNING APPARATUS Filed Jan. 11, 1956 8 Sheets-Sheet 3gwue/wkw ,47

Wcfor H Je Very Gum/Maw July 20, 1937. v. H. SEVERY TUNING 'APPARATUSFiled Jan. 11, 1936 8 Sheets-Sheet 4 July 20,, 1937. V. H. SE 2,087,485

TUNING APPARATUS Filed Jan. 3.1, 1936 8 Sheets-Sheet 5 Vkkfaf Sex 92yJuly 20, 1937. v. H. SEVERY TUNING APPARATUS 8 Sheets-Sheet 6 Filed Jan.11, 1936 I/fcfor H Jevery July 20, 1937.

V. H. SEVERY TUNING APPARATUS Filed Jan. 11, 1936 8 SheetsSheet 7 AMAAka/7MP L000 Saw/rte awe/WM Vfcfor [2. Jeremy July 20, 1937. v. H.SEVERY TUNING APPARATUS Filed Jan. 11, 1936 8 Sheets-Sheet 8 V/czorH J9Very Patented July 20, 1931 UNITED STATES PATENT OFFICE TUNING APPARATUSVictor B. Severy, Glendale, Calif.

Application January 11, 1936, Serial No. 58,691

21 Claims.

This invention relates to tuning apparatus,

. and while features of the invention may be employed in apparatus fortuning different kinds of musical instruments, the invention isparticuiarly adapted for use in tuning reed instruments, such asharmonicas.

One of the objects of the invention is to provide simple apparatusoperating on a beat principle, to facilitate tuning of the reeds of areed instrument, for example, a harmonica; also to provide thesame withmeans for indicating the recurrence of the beats when tuning a reed.

The apparatus preferably includes a carriage, which is movablelongitudinally of the reed plate which is supported in a holder when thereeds are being tuned, and one of the objects of the invention is toprovide simple means for enabling tools supported'in the carriage forremoving material from the reed near its fixed end or near its 29freeend, to'be' brought into alignment successively with the reeds thatare to be tuned.

A further object of the invention is to provide simple apparatusinvolving the use of two tools a having simple driving means foractuating the same and capable of being advanced alternately intoengagement with the reed being tuned to remove material from the reednear its fixed end,

or near itsi'ree end to change the frequency of vibration of the reedwhen the same is out of tune.

A further object of the invention is to provide a. simple tuningapparatus for the reeds of a reed instrument, which in use, willindicate visu- ..ally whether a; reed which is being vibrated isvibrating at its proper frequency to produce the note that the reedshould produce.

Afurther object of the invention is to produce improved means forclamping the reed plate in the holder. Y

Further objects of the invention will appear hereinafter. I

The invention consists in the novel parts and combination of parts to bedescribed hereinafter, all of which contribute to produce an efficienttuning apparatus.

A preferred embodiment of the invention is described in the followingspecification, while the ,broad scope of the invention is pointed out inthe appended claims.

In the drawings:

Figurel is an end elevation of a tuning apparatus embodying myinvention.

Fig.. 2 is a vertical section through the tuning apparatus illustratedin Fig. 1 and illustrating details of the preferred construction.

Fig. 3 is a vertical section through a portion of the apparatus takenabout on the line 3-3 of Fig. 2.

Fig. 4 is a vertical section taken about on the line 4-4 of Fig. 2, butupon an enlarged scale, and particularly illustrating the reed plateheld in the reed holder, together with means for clamping the reed platein position.

Fig. 5 is a section upon an enlarged scale taken about on the line 5-5of Fig. 2, and particularly illustrating the arrangement of backingmeans for backing up the reeds of the reed plate when the same are beingengaged by the cutting tools to remove a portion of the material,certain parts being broken away. 15 n Fig. 6 is a section taken about onthe line 6-6 of Fig. 2 upon an enlarged scale, and further illustratingthe means for supporting the tools on the carriage, certain parts beingbroken away.

Fig. 7 is a vertical section through an inner casing of the instrument,and illustrating the means for mounting the tuning forks and other---apparatus associated with the same.

Fig. 8 is a horizontal section taken about on the line 8-4 of Fig. '7,and further illustrating the arrangement of the tuning forks. Fig. 9 isa section taken on the line 9-4 of Fig. 8, and further illustrating themeans for mounting the forks to insure perfect insulation of the forksfrom each other to prevent interference.

Fig. 10 is a fragmentary view upon an enlarged scale, and illustratesthe means for mounting a lever that controls a clamping means to be usedwith the holder that supports the reed plate whenits reeds are beingtuned.

Fig. 11 is a horizontal section taken about on the line lI--ll of Fig. 2upon an enlarged scale, and further illustrating details of the clampingmeans for clamping the lower edge of the reed plate, certain parts beingbroken away.

Fig. 12 is a view showing an embodiment of the apparatus, in which thetuning of the reed may be efiected through the use of a flashing neonlamp. This view includes a diagram of the wiring employed in thisembodiment.

Fig. 13 is a diagrammatic view illustrating graphically the manner inwhich the circuit voltage is built up by the recurrence of beats toattain a voltage capable of operating a flashing lamp or light toindicate when the beats are occurring.

Fig. 14 is a diagrammatic view indicating the character of the voltagecurves in the circuit developed by the standard fork vibration, anddeveloped by the reed that is under test.

Fig. 15 is a. diagrammatic view of a portion of the apparatuscooperating in the tuning of a single reed, and illustrating the use oftranslating means in the circuit for indicating whether the reed is intune or not.

Fig. 16 is a front elevation of the switchboard as viewed from the planeof the line Iii-l6 in Fig. 1.

Fig. 17 is a diagrammatic view illustrating the general arrangement ofmy apparatus in which I employ a cathode tube as a translating devicefor indicating the recurrence of beats in the testing circuit.

Fig. 18 is a diagrammatic view illustrating details of the wiring to thecathode tube.

Fig. 190. is a diagrammatic view illustrating a phase of the image caston the fluorescent screen of the cathode tube.

Figs. 19b, 19c, 19d, and 19e, indicate different phases of the imagecast on the fluorescent screen of the cathode tube.

Before proceeding to a detailed description of the invention, it shouldbe stated that the apparatus operates on the beat principle. In oneembodiment of the invention, through the medium of the reed or vibratorthat is to be tuned, I develop impulses in an electric circuit, andthese impulses are amplified into a circuit having considerable voltage.By any suitable means, for example, a standard tuning fork and meanscooperating with it, amplified impulses are imposed into the amplifiedcircuit having substantially the same voltage as the impulses imposedinto the amplified circuit through the medium of the vibrating reed tobe tuned. The impulses imposed into the amplified circuit by the tuningfork have the frequency that the reed should have if his in tune. If thereed is not in perfect tune, then beats will occur in the amplifiedcircuit, and these beats will recur at less frequency, the nearer thereed is in tune with the tuning fork. Connected with the amplifiedcircuit I provide translating means for indicating the recurrence ofthese beats. A neon lamp, or a. voltmeter, may be employed for thispurpose as a. translating device, the lamp having a construction whichwill require a voltage to make it glow or flash, which is substantiallythe same as the combined voltages of the two imposed sets of impulseswhen they unite to form a beat.

The apparatus for practical purposes preferably includes three tuningforks as a unit to cooperate with each reed that is to be tuned; one ofthese forks having exactly the frequency that the reed should have ifproperly tuned, while one of the other forks has a frequency slightlybelow that of the reed if properly tuned, and the other fork having afrequency slightly higher. In making a test of a reed to ascertainwhether it is in tune, if the beats in the amplified circuit occur at avery low frequency, the reed will be considered as sufficiently in tune,but if the beats recur at such a frequency as to indicate that the reedis not sufiiciently in tune, then the impulses being imposed into theamplified circuit from the correct or "true tuning fork are cut out ofthe circuit, and impulses from one of the other tuning forks are imposedinto the circuit. The rate of recurrence of the beats will indicatewhether the reed is flat or sharp. Mechanism is provided for moving asmall quantity of material from the reed near its fixed end or near itsfree end, to alter its frequency in the direcace-mas tion indicated bythe recurrence of the beats. In this way the reed is brought into tune.

The mechanism for cutting or abrading material from the reed to bring itinto tune, is mounted in front of a holder in which the reed platecarrying the reeds is secured, and this mechanism includes two driventools which are driven through a common flexible drive enabling eitherone of the tools to be advanced into engagement with the reed withoutadvancing the other, although maintaining the drive to both tools. .Thetools are preferably mounted on a carriage, which is guided to movelongitudinally of thereed plate, and advances along its guide with astep-by-step movement, so that the tools are brought into alignmentsuccessively with the different reeds that are to be tuned. As the reedsof reed instruments such as harmonicas, are of graduated length, I haveprovided means for shifting one of the cutters or abrading tools so thatit adapts its position to the length of the reed on which it is tooperate.

In another embodiment of the invention, I provide simpler means foreffecting the tuning of a reed. In accordance with this embodiment ofthe invention, I utilize a set of three tuning forks including a correctfork, which will impose impulses into a circuit at exactly the frequencythat the reed being tuned should have if in tune. This set of threetuning forks includes also, two forks vibrating respectively, at a.slightly higher frequency and at a slightly lower frequency than thecorrect fork. In tuning a reed, the reed is vibrated by pneumatic meansor other suitable means, and is mounted so as to reflect a beam of lightfrom a flashing lamp, such as a neon lamp, which is first cut into theamplified circuit which is receiving impulses at the frequency of thecorrect fork. The beam from the lamp impinging upon the vibrating reedis reflected to the eye of the tuner, preferably through an observationwindow. If the reed is in tune and the flashing of the lamp is at thesame frequency as the correct fork, then the reed as viewed through theobservation window, will apparently be'standing still. If the reed, whenso tested, is apparently moving, then the correct fork must be cut outof the circuit, and one of the other two forks of the set out inalternately; and the action of the reed as viewed through the window,will then indicate whether the reed is flat or sharp.

In another embodiment of the invention I employ a cathode tube having afluorescent screen at its end, upon which the cathode beam impinges. Iprovide the interior of this tube with two sets of opposed platesarranged in pairs, and one pair of these plates is capable of beingconnected up to impulse generators, such as forks, so that these plateswill receive amplified impulses and operate to rotate the cathode beampassing between the same. The other pair of plates are preferablydisposed in a plane substantially at right angles to the first pair, andthey are connected up to a circuit in which amplified impulses aregenerated through the medium of the reed to be tuned. These platesaffect the form of the beam impinging upon the fluorescent screen, andenable this figure to indicate whether lustrated a reed plate 4 of aharmonica carrying a plurality of reeds 5. In front of the holder 3 acasing 6 is provided for housing the tools, and the operating mechanismfor the same. These tools are employed to cut off or abrade from thesurface of the reed, a small quantity of the material either near thefixed end of the reed, or near the free end.

Referring more particularly to Fig. 2, the reed plate is mounted on aseat I on the front of the holder, and the reeds 5 extend upwardlytoward their free ends. Each reed vibrates in a reed slot 8'in the reedplate. Back of each reed slot 8 a chamber 9 is formed, whichcommunicates through a port ID with a valve II, which is controlled bytwo levers l2 and I3 so that this valve can be opened at will bydepressing a plunger l4 near the forward edge of the table. The valves lare located in a suction box or vacuum box |5 to which a hose I6connects, said hose leading to an air pump, which maintains a partialvacuum in the suction box. In the suction box IS a pick-up devicesensitive to the vibrations of air occasioned by the vibrating reed, ismounted. In.

the present instance this pick-up device is in the form of a microphoneWhen the valve H is open, air is drawn in through the reed slot 8, andthe reed is vibrated and produces its note. The vibration of the reedimparts vibrations at the same frequency to the air passing down throughthe valve into the suction box, and sets up vibrations in the diaphragmI8 of the microphone at the same frequency as the reed. The microphoneI1 is connected up into a circuit that will be described hereinafter,and which is provided with means for imposing into an amplified circuitthe impulses at the same frequency as the vibration of the reed. If thetest of the reed indicates that it is in tune, the tool mechanism ismoved on to the next reed. If it happens that a reed is flat or sharp,then a small amount of material must be removed toward one or the otherend of the reed, as will now be described.

The tool mechanism preferably comprises a carriage |9 mounted to slidealong a guideway 20, so that the carriage can slide longitudinally ofthere'ed plate 4 (see Fig. 3). After operating upon a reed that has beentuned, the carriage is released by moving a hand-controlled detent 20which projects up against one of a series of dogs 2|, which constitute arack on the under side of the carriage (see Fig. 3). The carriage ispreferably constrained in one direction by means of a spring, forexample, a coil spring 22. Fig. 3 shows the carriage located at itsextreme right position; but by depressing the thumb plate of a lever 23the detent 20 can be depressed below the tooth or dog 2|, which it isengaging, and if it is quickly released it will move back to an elevatedposition in front of the next dog or tooth 2|. In this way the cuttingor abrading tools mounted on the carriage will be moved over intoalignment with the next reed. On the carriage I9 the easing 6 for thetool mechanism is mounted. Within this casing 6 I provide two toolspreferably in the form of rotary grinding discs, including an upper disc24 and a lower disc 25. These discs 25 and 25 are driven by a flexibledrive, which is so constructed that although the drive to the discs iscommon to both of them, either disc can be advanced to engage the reedat will. For this purpose the lower abrading disc 25 is mounted on aslide 26 that is guided in a horizontal guide 21 (see Fig. 3). The upperdisc 24 is mounted in a somewhat similar manner, but on account of thegraduated length of the reeds it must move down wardly as the carriageadvances along the reed plate so as to keep it in line with a point nearthe tip of the smaller reeds. For this purpose the grinder or disc 24 ismounted on a slide 28 that slides in a guide 29 that is supported at itsrear end on a pivot pin 30. Just above the forward end of the guide 29an inclined guide bar 3| is provided, against the under side of whichthe forward end of the guide 29 is held by resilient means, such as acoil spring 32. With this arrangement it will be evident that as thecarriage moves along the reed plate, the position of the upper disc 24will change to maintain the disc at about the level of the upper ends ofthe reeds.

In order to drive the discs, I prefer to provide a small electric motor33 mounted on the carriage, and the shaft of this motor is connected bya suitable coupling to a driven shaft 34, said shaft '34 being suitablymounted in the casing 9 and carrying a drive pulley 35 (see Fig. 2). Acontinuous resilient round belt 35, preferably consisting of a coilspring, passes over the drive pulley 35. and is disposed in twoforwardly extending loops that pass around driven pulleys 3i and 38 thatare rigid with the shafts of the discs 24 and 25. Between the drivenpulleys and near the drive pulley 35 a small guide pulley 39 is pro=vided, which assists in forming the forwardly extending loops in thedriving belt.

In order to enable either of the grinding discs 24 or 25 to be advancedat will, the rear end of each of the slides 26 and 28 is provided with aplunger 49, 4|, and these plungers are guided through the forward wall42 of the casing 8. The driving pulley 35 is mounted in a fixed braclret43 on the carriage, and this bracket also carries a small guide pulley39.

The carriage I9 is carried on a base 44 (see Fig. 3) provided with aguide tongue 45 that enables the carriage to be moved bodily toward theholder 3.

When either of the tools 24 or 25 is advanced against the reed 5 toabrade some of its material, it is necessary to back up the reedopposite the tool. For this purpose I provide a slide plate or block 46that slides horizontally through the holder, and having an inclinedforward face ll. The forward end of each slide or block 45 may beprojected forward chamber 9 back of the reed, so that the inclined face41 will fit up against the reed. Each slide 46 or block, may be advancedat will by an individual lever 48, which is returned by a return spring49, and the rear end of each block 46 is provided with an adjustablestop 59 for limiting the forward movement of the block when it moves upinto position.

The means for clamping the reed plate t on a seat I of the holder 3,will now be described. For this purpose I prefer to provide a coverplate 5| (see Fig. 2) that rests on the upper face of the holder 3, andthe forward edge of this cover plate carries brackets 52 through whichthe shaft; 53 extends, said shaft having an actuating lever 54, with alatch 55 to cooperate with a notch 55 in the bracket 52 to hold theshaft 53 in a raised position when the reed plate is to be removed. Thisshaft 55 carries a plurality of rigid clamping arms 5i, which arepreferably bent as shown in Fig. 2, and a coil spring 53 is provided forpulling these clamping arms down against the reed plate 4 at its upperedge. The rear edge of the cover plate 5i is mounted on a shaft 59similar to the shaft 53, and this shaft is provided with a lever intoits corresponding I withdrawing from the same.

60, and mounted to rotate in brackets iii. The lever 60 has a latch 62to cooperate with a notch 63 in oneof the brackets Iii. When the lever60 is rotated toward the right, the cover plate 5| will be swung up intoan elevated position so as to clear the way for the introduction of areed plate from above, down onto the seat I at the forward side of theholder..

For holding the lower edge of the reed plate 4 against the seat I, Iprefer to provide a shaft 54 rotatably mounted in brackets 65 attachedto the ends of the holder 3 (see Fig. and at a plurality of points alongits length, this shaft is provided witheccentrics or cams 60, said camsbeing spaced apart and each cam being mounted in a bracket 61 attachedto a pad 88 (see Fig. 11) and operating so that when the shaft isrotated, each eccentric will press its pad against the forward face ofthe reed plate. Each bracket 61 has means for holding it on the shaft,and for this purpose each bracket is preferably provided with two wingplates 60 with a large slot or opening 10 formed in them, providingclearance for the shaft when it rotates,'and permitting the bracket 61to move to and fro in applying the pad 60 to the forward face of thereed plate and This shaft 64 may be rotated at will by a lever II, whichis urged to a position to apply the pads 68 tothe reed plates, by a coilspring 12 (see Fig. 10) that normally holds the lever II up against afixed stop 13 on oneof the brackets 65.

The preferred arrangement of my apparatus and wiring for the same isindicated in Fig, 15. This diagram illustrates a unit for tuning'asingle reed involving the use of three forks indicated generally by thenumeral II, and including an in-- termediate fork 'Ilb, which I call thecorrect fork, and two other forks Ila. and He. The -correct" fork 10bshould vibrate at a frequency which is the same as that of the reedbeing tuned if the reed is in tune. In other words. ithas the frequencythat the reed is to be tuned to. The

fork 14a. has a frequency. slightly below that of the fork 14b, and thefork "c has a frequency slightly higher than the fork 10b. These forksand the apparatus that corresponds to each fork, are wired in parallelto a selector switch I5 indicated diagrammatically in Fig. 15, and, alsosufficient to describe the apparatus and wiring associated with onefork, for example, the fork "a. The apparatus associated with each forkis such that when the movable contact member I0 of the switch I5 is inengagement with a contact such as the contact 15a. corresponding to acertain fork, the fork will immediately commence to vibrate and developimpulses in its local circuit at the frequency of the fork. In theapparatus as illustrated in Fig. 15, the tine 18a of the fork Ilainitiates the vibrating movement of the fork when the contact 15a andits corresponding wire I1 is connected up into the circuit by themovable switch member I8. When the circuit is closed at this point,impulses are passed into an amplifier 19 from a main circuit system tobe described hereinafter, impulses from which are developed at thefrequency of the reed that other terminal on this side of the amplifier.

is to be tuned. The other side of the amplifier I9 is connected with theprimary ll of a transformer 82, the secondary coil 83 of which isconnected with coils 84 on a permanent bipolar magnet 85, the poles ofwhich are adjacent to the outer face of the fork 18a. From the other endof the primary coil 0i a conductor or wire llm leads through a triodetube 80 to a conductor or wire 81 connected through a condenser 00 tothe In order to place bias on the plate of the triode tube 85, aresistance 80 and a condenser 90 are connected into the wire 00 and thetube, as indicated. The same terminal of the amplifier that is connectedwith the wire 00, connects with a wire or conductor 9i leading through abattery 82 and to a conductor or wire 03 beyond the battery that isconnected to a coil 94 of a bipolar magnet, the poles of which are nearthe face of the tine 10b lying opposite a tine 10a. The other side ofthe coils 94 are connected to the wire 81 leading back to the amplifierI0. It will be evident that this apparatus has a regenerative action asregards the tuning fork, so that the resiliency of the fork and arecurrence of the impulses in the fork circuit will maintain the fork incontinuous vibration as long as the contact I 15a is connected intocircuit through wire 05 that is connected up with the common wiringsystem associated with the vibrating reed. Hence, whenever one of theforks Ila, "b, or No is connected up into the circuit, impulses will bedeveloped in the circuit at the frequency of that particular fork. Theseimpulse frequencies are imposed into the main circuit systemsimultaneously with impulses imposed into that system through theagency-of the vibrating reed plate,

thereby generating. beats. The preferred com- -mon wiring arrangementassociated with the reed will now be described. This apparatus involvesthe use of a preamplifier 00, one side of which is connected by circuitwires 91 and 00 with the microphone II. The other side of thepreamplifier 00 is connected by wires 00 and I00 to an amplifier IOI.One of the terminals of the a other side of the amplifier MI isconnected to a wire I02 connected up to a flashing neon lamp I03, and aloud speaker I00 if desired, the said lamp and loud speaker beingconnected in parallel on circuit wires I05 and I08 leading over to areturn wire I01, which wire I01 is connected in parallel to all thewiresll of. the local fork circuits through suitable switches I00. Ifdesired, a voltmeter V may be connected into a conductor I09,between thewire I02 and the wire I05, and provided" with a switch III for cuttingthe voltmeter in or out of circuit. The neon lamp wire I0! is alsoprovided with a switch III.

A conductor 2 also connects with the wire I02 through a variablemodulator resistance III, and this wire H2 leads to the pivot of themovable contact ll of the selector switch II. A similar variablemodulator resistance III is provided in connection with the conductorIll, and leading off from the amplifier Ill.

In Fig. 18, I illustrate the face of the switchboard on which isindicated the selector switch I5 and the three switches I00 for cuttingin the branches of the circuit leading through the three forks. In'thisview handles 3a and Illa are illustrated running in slots in the face ofthe board, for controlling the two modulator resistances H3 and III.

The board also carries a dial V for the voltmeter, and indicates thevoltmeter switch I II and bases H6 also support the coils 84 and 94 forthe electromagnets. The forks are preferably mounted in the lowerportion of the box, and an inner cover I I8 is provided for the box,which may carry the triode. tube 85 and the casing I I9 for carrying theamplifiers and preamplifiers of the system.

By reason of the fact that each fork is individually insulated below andon all sides at its base, there is no possibility of the vibrations fromone fork being imparted through the fork supports to adjacent forks.

In the operation of the testing apparatus described, it should beunderstood that impulses are imposed into the circuit at the frequencyof the reed being tuned, said impulses being amplifled in the indicatingcircuit, so that the current flowing through the neon lamp would have asubstantial voltage, for example fifty volts. This current of course,will be a wave current, and in Fig. 13, I have illustrated its phasesdiagrammatically by a full line I20. When the selector switch I5 isclosed through the contact 15b to connect up the correct test fork 14b,impulses will be imposed into the indicating circuit at substantiallythe same voltage as those of the impulses that are being imposed intothe circuit through the agency of the reed, for example, fifty volts.The character of this impulse current generated through the agency ofthe fork, is indicated by the dotted wave line I2I in Fig. 13. Thesecurrents should be substantially equal, and should be made so byadjusting the modulator resistances H3 and H4. It will be evident thatif the reed is not vibrating at the same frequency as the fork 1411, thetwo sets of impulses in the circuit will generate beats. When thevoltages from the .two sets of impulses are alike at the same instant,this will give substantially double the voltage when this heat occurs,as indicated by the dotted wave line I22.

This beat is utilized by means of a translating device, which will beaffected by this increased voltage occur-ring at a beat, but which willnot be affected by the normal voltage developed by either of theimpulses in the circuit. This translating device preferably takes theform of a neon lamp, such as the lamp I03, said lamp being constructedso that it will not flash for fifty volts. but will flash for onehundred volts. While the impulses from the reed and from the fork 14bare passing simultaneously through the circuits, if the reed is notexactly in tune, beats will occur;

.- and. whenever a beat occurs or recurs, the neon lamp will flash. Therapidity of recurrence of these beatsis an index of the amountthat thereed is out of tune. If the reed is sharp, then the speed of recurrenceof these flashes will be increased by cutting in to the indicatingcircuit,

the fork 14a, which vibrates at a lower frequency. By doing this andobserving the recurrence of the flashes, the-tuner can ascertain whetherthe reed is sharp or flat, and will then tune the reed accordingly.

In Fig. 12, I illustrate an embodiment of my invention in which Iutilize the flashing frequency of a lamp of the neon type to enable areed to be tuned. In this instance I provide a holder I23 in which areed plate I24 is mounted, and before which grinding tools I25 aremounted and within the casing or housing I26 I provide a flashing lampI2'I of the neon type, in a posi tion to throw a beam of light onto thevibrating reed I28, so that the reflected ray will pass through anobservation window I29 in the easing. Through the medium of a suctionbox I30 and a valve I3I, the reed that is to be tuned is vibrated. Thelamp I2! is connected up through conductors I32 and I33 to apreamplifier I34, and

this preamplifier is connected through a conductor I35 to an amplifierI30 connected up to a plurality of. tuning forks I3'I through aplurality of conductors I38. In other words, the electromagnets I39 andI40 that cooperate with the tines of these forks, are connected up inparallel between the amplifier I35 and a return wire I4I that isconnected with the terminal I43 and amplifier I34, through a condenserI44. The terminal I45 opposite the terminal I43, connects with aconductor I46 carrying a battery I the opposite side of which isconnected to a movable switch member I48 guided to move along thecontact bar I49, so that its tip can be brought at will into engagementwith contacts I50 that are connected by wires I5I with the conductorI4I. These contacts I50 are preferably arranged in sets of three likethe contacts of the selector switch I5, so that contacts I50 which aremounted on an insulating bar I5I, cooperate with the movable contact I48to constitute a selective switch.

In using this apparatus for tuning, suppose for example, the reed I28should vibrate at the same frequency as the correct fork I3Ib. In thatcase, the movable contact I48 would be placed on the contact I50b, as aresult of which the lamp I2I will flash at the same frequency as thefrequency of the fork I3Ib. If this fre quency is the same as that ofthe reed I28, then to the eye of an observer at the window I29, the reedI28 will apparently be standing still. If the reed I28 is not in tunewith the fork I3'Ib, then the tuner will move the contact I48 in contactwith either of the two contacts of the set of three corresponding tothat need, thereby throwing in either of the outside forks I31 of theset, one of which vibrates at a slightly lower frequency than the forkI31b, and the other of which vibrates at a higher frequency. If. thereed I28 is more nearly in tune with the fork having a higher frequency,it will appear to have less movement when observed through the window atI29 than when the lamp is being flashed by the fork at the other end ofthe trio of forks.

If desired, a second neon lamp I52 may be connected up in series withthe lamp I21, and located in such a way as to eliminate shadows withinthe casing I26. With the tuning apparatus illustrated in Fig. 12, itwill be evident that the operation of this apparatus also depends uponthe beat principle, for if the reed is in tune with the middle fork ofthe set, no visual beats will be apparent to the observers eye in thewindow I29. If it is not in tune with the middle fork I3Ib, andvibrating at the same frequency as the flashing lamp I 21, then visualbeats will' tion of the reed to the microphone I1, and the microphonecurrent passes through the preampliher 98 and the amplifier I0], and theamplified impulses occur in the conductor H2 that leads to the movablecontact 18 of the selector switch 15. This contact I8 should then beplaced on the contact b that corresponds to the correct tuning fork 14bwith which the reed should be in tune. The vibration of this fork willimpose amplified impulses into the circuit at the same frequency as thefork 14b. If this frequency is the same as that of the reed, the neonlamp I03 will not flash. However, if the reed is not in tune with thefork 14b, beats will occur as indicated in Fig. 13, and when these beatsoccur the voltage through the neon lamp will be approximately onehundred volts, which is double that of the voltages being developedthrough the agency of the reed and through the agency of the fork 14b.Inother words, whenever a beat occurs, the voltage will be, high enoughto flash the neon lamp. If, in tuning, the reed, beats occur at asufllcient frequency to necessitate tuning the reed, then the tuner willmove the movable contact 18 of the selector switch 15 to engage thecontact 15a, or the contact 15c alternately. As the contact 150. isconnected up with the fork Ha that vibrates at a slower frequency thanthe fork Nb, it follows that if this fork 14a is connected up into thecircuit, the beats will recur at a slower rate if the reed is flat. Onthe other hand, if the fork He is connected into the circuit and thereed is flat, the beats in the circuit will recur at a more rapid rate.In other words, the neon lamp I03 will flash faster.

The beats can also be observed by the ear applied to the loud speakerI04, and they will also .be indicated more or less in the voltmeter V.

When it is ascertained whether the reed is fast or slow, then materialis removed from the face of the reed 5 through the agency of one of thetools ll and 25 illustrated in Fig. 2.

In tuning the reeds, the reed plate is set up so that the longest reedis located at the right,

as viewed in Fig. 3. After tuning this reed, the tuner depresses theleverv 23, which releases detent 20 (see Fig. 3) from the dog 2|,permitting the slide I! to move toward the left through the spacebetween the dogs 21. This will align the tools 24 and 25 with. the nextreed which is to be tuned. As the carriage proceeds in this waylongitudinally of the reed plate, the guide 29 that carries theuppermost tool 24, which engages with the inclined guide bar 3i,depresses the guide 29 by rotating it about its pivot 30 (see Fig. 2).In this way, the tool 24 is caused to move along an inclined line tokeep it substantially aligned with the tips of the reeds, which shortentoward the opposite end of the reed up by the slide block 46.

' as the note, and the diflerent forks of the set corresponding to thisnote, would be cut in alternately into the circuit, to determine therate of recurrence of beats in the neon lamp.

In Fig. 17, I illustrate the employment of a cathode tube with theelectrical apparatus of Fig. 12, as a visual translating device. In thiscase the test impulse generators such as the tuning forks l53a, ltlb,and lilo, are connected by a wiring system I the same as shown in Fig.12, to a cathode tube I55 through a preamplifler I56 and an amplifierI51, said wiring system including modulators I58 and I58 connected uprespectively to pairs of terminal plates I60 and I8! (see Fig. 18). Theplates of one pair are in a plane substantially at right angles to theplane of the other pair. The cathode tube has a fluorescent screen I62against which the oathode beam impinges. The plates IBI are preferablysubstantially vertical. As the cathode ray passes through the tube, ifonly the test impulses are passing in the circuit, then the eye I63 ofthe tuner will see a fluorescent figure on the screen "52 having atleast some of the phases illustrated in Figs. 19a, 19b, 19c, 19d, and19e by the three cathode tubes i55a, "5b, I550, lild, and Mic, but withthe figure maintaining fixed axes for itself. But when impulses aredeveloped in the test circuit through the agency of a reed I to betuned, the axis of the figure on the fluorescent screen will appear torotate due to the rotating effect of the plates III! on the oathode ray;and this axis-rotation will take place regardlessof whether the two setsof impulses in the test circuit are in phase or not. The speed ofrotation of this axis indicates the speed or rate of recurrence of thebeats. Hence by alternately cutting the different forks liia, I532 andI530, into the circuit, the tuner can ascertain whether the reed beingtuned is fast or slow.

' It is understood that the embodiment of the invention described hereinis only one of the many embodiments this invention may take, and I donot wish to be limited in the practice of the invention, nor in theclaims, to the particular embodiment set forth.

What I claim is:

1. In tuning apparatus for an instrument having vibrators, thecombination of an electric circuit, pneumatic means for vibrating thevibrator at its natural rate, means energized by the vibrating vibratorfor imparting impulses to the electric current flowing in the circuit atthe frequency of the vibrator that is to be tuned, means for impartingimpulses to the circuit at a constant known frequency approximately thesame as the first-named frequency to produce beats in the circuit, and atranslating device connected to the circuit for indicating the rate ofrecurrence of the beats.

2. In tuning apparatus for an instrument having vibrators, thecombination of an electric circuit, means for vibrating the vibrator atits natural rate, means energized by the vibrating vibratorfor-imparting impulses to the electric current flowing in the circuit atthe frequency of the vibrator that is to be tuned, said circuitincluding a branch with means therein for imparting impulses into thecircuit at a constant known frequency, and other branches with means ineach of the same for imparting impulses to the circuit respectively atconstant known frequencies respectively, having a higher and lower ratethan the first-named known frequencies, a switch for enabling any one ofsaid branches to be brought into the circuit, thereby causing beats inthe circuit, and a translating device in the circuit for indicating therate of recurrence of the beats.

3. In tuning apparatus for tuning the vibrators of a musical instrument,the combination of a circuit with means for imparting impulses to thebrator being tuned, said switch having a pair of auxiliary contacts, oneof said last-named auxiliary contacts having a branch corresponding tothe same with means in that branch for imparting impulses to the circuitat a slightly higher constant frequency than that of the first-namedbranch, the other of said contacts having a branch connected therewithwith means in that branch for imparting impulses to the circuit at aconstant frequency slightly lower than that of the first-named branch,said switch enabling the difierent branches to be brought individuallyinto circuit to cause beats in the circuit, and means in the circuit forindicating recurrence of the said beats.

4. In tuning apparatus for an instrument having vibrators, thecombination of an electric circuit with means for imparting impulses tothe electric current flowing in the circuit at the frequency of thevibrator that is to be tuned, means for imparting impulses to thecircuit at a constant known frequency approximately the same as thefirst-named frequency to produce beats in the circuit, and a neon lightin the circuit operating to light by the voltage of the beats butremaining dark under the voltage in the circuit below that occasioned bythe beats.

5. In tuning apparatus for tuning a harmonica having a reed plate withreeds attached to the same, the combination of a holder for the reedplate, a carriage with means for guiding the carriage to movelongitudinally of the reed plate, two tools carried by the carriage withmeans for guiding the same to enable either of the tools to be advancedto engage a reed to remove a por- 5 tion of the material thereof, andmeans for effecting the advance of the carriage with astep-bystepmovement longitudinally of the reed plate so as to align thetools successively with the different reeds.

f '6. In tuning apparatus for tuning a harmonica having a reed platewith reeds attached to the same, the combination of a holder for thereed plate, a carriage with means for guiding the carriage to movelongitudinally of the reed plate,

two'to'ols carried by the carriage with means for guiding the same toenable either of the tools to beadvanced to engage a reed to remove aportion of the material thereof, means for effecting the advance of thecarriage with a step-by-step -movement longitudinally of the reed plateto align the tools successively with the different reeds, and ahand-controlled slide capable of moving in back of the reed that isengaged by either of the tools to back up the same while in engagementwith the tool.

'7. In tuning apparatus for tuning a harmonica having a reed plate withreeds attached to the same, the combination of a holder for the reedplate, a carriage with means for guiding the carriage to movelongitudinally of the reed plate, two tools carried by the carriage withmeans for guiding the same to enable either of the tools to be advancedto engage a reed to remove a portion of the material thereof, a commonflexible driving means for driving both of the tools, enabling eitherof. the .tools to be advanced to engage the reed without advancing theother tool, and means for effecting the advance of the carriage with astep-by-step movement longitudinally of the reed plate to align thetools successively with the different reeds.

8. In tuning apparatus for tuning a harmonica having a reed plate withreeds attached to the same, the combination of a holder for the reedplate, a carriage with means for guiding the carriage to movelongitudinally of the reed plate, two tools carried by the carriage withmeans for guiding the same to enable either of the tools to be advancedto engage a reed to remove a with the reed that is being tuned, andmeans for efiecting the advance of the carriage with a stepby-stepmovement longitudinally of the reed plate to align the toolssuccessively with the difierent reeds.

9. In tuning apparatus for tuning a harmonica having a reed plate withreeds attached to the same, the combination of a holder for the reedplate, a pair of rotary tools with means for supporting the same infront of the reed plate, a common flexible driving means for both ofsaid tools with means for guiding said tools to enable either tool to beadvanced into engagement with the reed to remove a portion of thematerial thereof.

10. In tuning apparatus for tuning a harmonica having a reed plate withreeds attached to the same, the combination of a holder for the reedplate, a carriage with means for supporting and guiding the same to movelongitudinally of the reed plate, said carriage having a rack thereon, amovable detent controllable at will, for engaging the rack, and a pairof tools mounted on the carriage with means for driving the same, saidrack and said detent cooperating to enable the carriage to be held indifferent positions to enable the tools to be aligned successively withthe difierent reeds.

11. In tuning apparatus for tuning a harmonica having a reed plate withreeds attached to the same, the combination of a holder for the reedplate, a carriage with means for supporting and guiding the same to movelongitudinally of the reed plate, said carriage having a rack thereon, amovable detent controllable at will, for engaging the rack, a pair oftools mounted on the carriage with means for driving the same, said rackand said detent cooperating to enable the carriage to be held indifferent positions to enable the tools to be aligned successively withthe different reeds, and means for urging the carriage to move in onedirection.

12. In tuning apparatus for an instrument having vibrators, thecombination of an electric circuit with means for imparting impulses tothe electric current flowing in the circuit at the frequency of thevibrator that is to be tuned, said circuit including a branch with meanstherein for imparting impulses into the circuit at a constant knownfrequency, and other branches with means in each of the same forimparting impulses to the circuit respectively at constant knownfrequencies respectively, having a higher and lower rate than thefirst-named known frequencies, a switch for enabling any one of saidbranches to be brought into the circuit, thereby causing. beats in thecircuit, and a flashing neon lamp in the circuit energized only by thebeats passing through the same and mounted in a position to enable thereed being tuned to reflect a light beam from the lamp.

13. In tuning apparatus for tuning a harmonica. having a reed plate withreeds attached thereto, the combination of a holder for the reed plate,means for vibrating the reed that is to be tuned, an electric circuit, aflashing lamp in said circuit, means for imposing impulses in thecurrent flowing in the circuit at the same frequency that the reedshould have if in tune, said holder operating to hold the reed plate sothat the reed being tuned will reflect a beam of light from the flashinglamp. 4

14. In tuning apparatus for tuning a harmonica having a reed plate withreeds attached thereto, the combination 0! a holder for the reed plate,means for vibrating the reed that is to be tuned, an electric circuit, aflashing lamp in said circuit,

' means for imposing impulses in the current flowing in the circuit atthe same frequency that the reed should have if in tune, said holderoperating to hold the reed plate so that the reed being tuned willreflect a beam of light from the flashing lamp, and a casing having anobservation window in the path of the beam after being reflected fromthe reed being tuned.

15. Intuning apparatus for tuning a harmonica having a reed plate withreeds attached thereto,

the combination of a holder for the reed plate, means for vibrating thereed that is to be tuned, an electric circuit, a flashing lamp in saidcircuit,

' means for imposing impulses in the current flowing in the circuit atthe same frequency that the reed should have if in tune, alternate meansfor imposing impulses in the current flowing in the circuit at a higherfrequency than the reed should have if in tune, and alternate means forimposing impulses in the current flowing in the circuit at a lowerfrequency than the reed should have ii in tune, and switch means forimposing the higher or lower frequency impulses into the circuit atwill, said holder operating to hold the reed plate so that the reedbeing tuned will reflect a beam of light from the flashing lamp.

16. In tuning apparatus for tuning a barmonica having a reed plate withreeds attached thereto, the combination of a holder for the reed plate,means for vibrating the reed that is to be tuned, a pair or tools withmeans for supporting the same in alignment with the reed to 1 be tuned,one oisaid tools being located near the'flxed end of the reed, and theother tool being located near the free end of the reed, an electriccircuit, a flashing neon lamp in said circuit, means for imposingimpulses in the current flowing in the circuit at the same frequencythat the reed should have if in tune, said holder operating to hold thereed plate so that the reed being tuned will reflect a beam of lightfrom the flashing neon lamp, an observation window in.

the path of the beam after being reflected from the reed being tuned,and means for advancing either of the tools into contact with the reedto the casing in line with the reed and located respectively near theflxed end of the reedand near the free end of the reed, an electriccircuit, a lamp mounted in the circuit below the level of the tools, aflashing neon lamp located in the circuit above the level of the tools,means for imposing impulses in the current flowing in the circuit at thesame frequency .that the reed should have if in tune, and means foralternately imposing impulses in the current flowing in the circuit athigher frequency and at lower frequency than that of the reed if intune, and an observation window in the casing, said holder operating tohold the reed plate so that the reed being tuned will reflect beams oflight from the flashing lamp.

18. In tuning apparatus for tuning the vibrators of a musicalinstrument, the combination of a circuit, a pick-up device in thecircuit mounted adjacent the vibrator that is to be tuned and operatingto impose impulses into'the said circuit at the same frequency as thatof the vibrator that is to be tuned, a multiple switch in the circuithaving a plurality of contacts arranged in sets of three, each setincluding an intermediate contact and end contacts, a circuit connectedwith the intermediate contact for imposing impulses into the circuit atthe same frequency as the vibrator being tuned would have if in tune,thereby producing beats in the said circuit, means connected with thecircuit for indicating the said beats, one of said end contacts of eachset of three having means connected therewith for imposing into thecircuit impulses at a constant frequency higher than that of thevibrator being tuned, and the other of said end contacts having meansconnected therewith for imposing impulses into the said circuit at aconstant frequency lower than that of the vibrator being tuned, the saidindicating means for indicating the beats cooperating with the circuitsto indicate whether the vibrator being tuned is sharp or flat.

19. In tuning apparatus for tuning a harmonica having a reed plate withreeds attached, to the same, the combination of a holder for the reedplate, a carriage with means for guidingthe'jcarriage to movelongitudinally of the reed plate, two tools carried by the carriage withmeans for guiding the same to enable either of the tools to be advancedto engage a reed to remove a portion of the material, thereof, means formovably supporting one of the tools on the carriage to enable the sameto be moved up or down, and relatively fixed guiding means for movingthe last-named means as the carriage advanceslongitudinally of the reedplate to enable the tool carried by the said last-named means ,tooperate upon a reed plate in which the reeds are of graduated length. g

20. In tuning apparatus for tuning a harmonica having a reed plate withreeds attached to the same, a holder for the reed plate having a seatfor the reed plate, a shaft extending longitudinally of the seat andlongitudinally of the reed plate when mounted on the seat, a pluralityof cams on the shaft, and means cooperating with the same so that whenthe shaft is rotated the reed plate will be clamped at a plurality ofpoints along its length.

21. In tuning apparatus for use by a vtuner in tuning the vibrators of amusical instrument, the combination of a circuit with means forimparting impulses to the circuit at the frequency of the vibrator thatis to be tuned, a

switch having a main contact corresponding to each vibrator to be tuned,a branch for the circuit leading from said main contact, with means inthat branch for imparting impulses to the circuit at a constant knownfrequency approximately the same as the frequency of the vibrator beingtuned, said switch having a pair of auxiliary contacts, one of saidlast-named auxiliary contacts having a branch correspond- 10 ing to thesame with means in that branch for imparting impulses to the circuit ata slightly higher constant frequency than that of the firstnamed branch,the other of said contacts having a branch connected therewith withmeans in that branch for imparting impulses to the circuit at a constantfrequency slightly lower than that of the first-named branch, saidswitch enabling the diiferent branches to be brought individually intocircuit to cause beats in the circult, and means in the circuitfor'indicatlng to the vision of the tuner the recurrence of the saidbeats.

. VICTOR H. SEVERY.

